Circuit protection.



G. WRIGHT. CIRCUIT PROTECTION. APPLICATION TILED D30. 26, 1913.

1,105,392. Patented July 28,1914.

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"entrain sra'rias PATENT orrios.

GILBERT WRIGHT, OF SCK-IENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, ii. CORPGRATIQN OF NEW YORK.

CIRCUIT PROTECTION.

Application filed December 26, 3.913.

To all Ac/zomit may concern Be it known that I, Giiasmrr \l'iuoii'r. acitizen of the United States, residing at Schnectady. county ofSchnectady, State of New York. have invented certain new and usefulImproverents in Circuit ln'tll ililtll llh of which the following is a,specification.

My in rention relates to circuit protection, its aim being to providefor the eitectuai interruption or disconnection of a circuit or aportion thereof upon the occurrence of abnormal conditions therein.

Among the more important advantages obtainable in connection. with myinvention. Imay mention certainty and reliability of action; theadequate protection of extensive circuits without substantialinterruption of service except in the portions or branches whence theabnormal conditions arise: and the ability to take care of the heaviestoverloads or short circuits by means of simple and inexpensiveapparatus. My invention is of special advantage for overload and. shortcircuit protection in connection with lighting and power distributioncircuits in the business and manufacturing sections of cities, whereuninterrupted service is of the utmost; importance, and I have hereindescribed the embodiment at present known to me with especial referenceto itseinploymcnt for such a purpose. Ti hile. however, the inventionextends to the ap' paratus as shown and described and to its specificfeatures and details it is not confined thereto, but can be otherwisecarried out and applied.

In multiple distribution systems such as above referred to, it is commonto provide means for opening the circuit in various parts of the systemunder conditions of excessive current flow arising from overload, shortcircuit. or other causes. As adequate protection of the system mayrequire the circuit to be broken automatically under currents amountingto almost the entire out put of the generating plant on heavy shortcircuit, and as this in turn necessitates costly apparatus kept incli'ective condition. the means for opening: the circuit usuallyiiicludcs a suitable overload circuit breaker for each main. line (whi his installed in the power house. substation. or other contral pointwhence the mains radiate) and fuses in each feeder or subcedar branch ofthat line and on the iremises of each current Specification of LettersPatent.

Patented July 28, 191%. Serial No. 808,645.

consumer connected thereto, etc, as well as hand operated switches atvarious points. While in practice this arrangement usually limits theinterruption of service due to abnormal conditions anywhere in the sys-(5:) tom to the main circuit on which they occur and makes the generalinterruption on that circuit very brief if the fuses in the feeder orbranch directly involved prove eil'ective,

it. is not always as satisfactory as could be wished. For example, if aconsumer shunts a fuse or (as some times happens) repairs a burned-outone with a piece of copper wire, the main line circuit breaker may blowin consequence of a short circuit on his premises without his branchcircuit being; cut oil the main line. and in thi case service cannot berestored in the line until this short circuit is removed. In accordancewith myinvention. such difiiculties are over- 7 come by the installationof automatically operating circuit breaker means in each branch orsection of the main circuit or on the premises or, the circuit of eachlarge consumer. or at other suitable points in the system. 'The circuitbreaker means thus employed come into action underconditions ofexcessive current flow. but do not open till a tter such conditions havec ased.--whether in consequence of the opening of the main circuitbreaker. the opening of a hand switch. or tor any other reason.so thatthe same can be made comparatively simple and inexpensive and at thesame time just as cfllicl'ive as the main circuit breaker with whichthey co-act. \Vhencver. theref re. a main circuit breaker opens. it canbe inmiediatcly closed again with the reasonable certainty that unlessthe trouble is on the line itself it has been cut oil; audit the line isarranged in sections connected together through such circuit breakermeans, trouble on a section of the line itsclt' need not in terruptservice on the sections between that one'and the main circuit breaker.

The accompanying drawing shows a very simple distribution circuitprotected in accordance with my ii'ivention.

The circuit shown comprises the main portion 1 having in it a circuitbreaker 2 of any approved type that opens in response to conditions ofexcessive current flow and a branch 3 derived from said main portion havinein it additional circuit breaker means 4 as well as the usualprotective fuse 5 for the circuits 6. (3 of a consumer. The circuitbreaker l comprises circuit interrupting means 7 for disconnecting thebranch 3 and nuulls' 8 responsive to conditions of excessiv curl' ntflow which causes the interrupting n'lcans T to open only a'fter suchcon-- ditions have ceased. The interrupting means 7 comprises a suitableswitch blade 9 pivoted at 10 a suitably mounted contact 11, a spring 12under whose influence the switch automatically tends to open, and adetent lever 13 fulcrumed at 1 1 by which pening of the switch isnormally prevented. The means 8 shown includes current respon sive meansproper consisting of a solenoid coil 15 connected in the circuit 3 and acore part 16 associated therewith,which latter at the proper time actsto trip and render ineffective the detent 13 and so serves as theoperating means for the switch 7. The operative connection through whichthis is effected is at the proper time formed by the engagement of aconical he: d or catch 17 on the core part 16 with a latch 18 pivoted tothe detent 13 at 19; normally, however, the core 16 and the catch 1'?occupy the lowermost, inoperative positions in which they are shown,with the catch 12' out of engagement with the latch 18 so that the Core16 is not in immediately operative connection therewith and 'isincapable of actuating, the .witch 7. Preferably the solenoid 15 is sodesignedwith or without regard to thenormal loads on the main portion 1of the circuitthat it will not be able to raise its core 16 except whenthe current in said branch 3 is so strong that opening of the maincircuit breaker 2 would result. If it desired that the circuit breaker ashould not open on momentary overload, or unless th ircuit breaker 2opens, or ahead of the circuit breaker 2 in the event of the currentfalling off before the latter actually opens, a suitable dashpot 20 maybe connected to the core 16; and similar means, may, if necessary, beemployed in connection with the circuit breaker 2 to insure that thecatch 17 shall pass the latch 18 before said circuit breaker 2 opens,etc.

The operation is as follows: If an oven load occurs on the circuit 6,the fuse 5 may be able to take care of it and effectually cut off thebranch "3 before the current becomes strong enough to open the maincircuit breaker 2. If, however, the current becomes so heavy that anarcforms between the terminals of the fuse 5, or if the fuse for anyother reason fails to cut, all the branch 3, the field ofthe solenoid 15will become strong enough to raise the core 16 till'the catch 17 tripspast the latch 18 into operative position with reference thereto, thusestablishing an operative connection be-- tween the detent 13 and thecore 16 and rendering the latter capable of actuating the switch itslong the excessive cur-- rentfiow continues, the core 16 will be sus--tained in its levated position and opening of the switch 7 will still beprevented; but as soon as the circuit is eliectually broken by theopening of the main circuit breaker 2.;--which will he )pen almostinstantly,- the core 16 will drop and operate on the latch 18 to tripopen the switch 7.v As this will also occur almost instantaneously, thecircuit brca 2 can be closed practically as soon as it opens and serviceon the other feeders or branches oi: the main lmaim taincd without anymaterial interruption, the circuit breaker 4 remaining open untillocally reset. I

For the suite of simplicity of illustration, only a sin le wire circuitis shown in the drawing. return wires luring omitted or replaced byrounds.-but it will be. undcrstood that my invention can be applied tocircuits of all sorts and that connection through any r all oi theconductors of the circuit can he interi ptcd by the circuit breakers E2and 4-. it is also to be under stood. of course. that my invention isappli cable to alternating or pulsating current cir cuits as well as tothose carrying: continuous. uniform. unidirectional current. and thattransformers, (YOHv'QI't-QIS, etc. may be tater-posed in the circuits asdesired.

\Vhat I claim new and desire to secure by Letters Patent of the. UnitedStates, is

1. In an electric circuit, the combination with circuit interruptingmeans therefor, of means responsive to conditions of excessive currentflow therein for causing said circuit interrupting means to open aftersuch conditions have ceased.

2. In an electric circuit the combination of circuit interrupting means,operating means for said circuit interrupting means not ordinarilycapable of actuating the same, and means responsive to conditions ofexcessive current flow for rendering said operating means capable ofactuating said circuit interrupting means and for preventing opening ofthe latter during the continuance of such conditions.

3. In an electric circuit the combination of a circuit breaker foropening the circuit under conditions of excessive current flow andadditional circuit breaker means that comes into action under likeconditions but opens only after such conditions have ceased.

4. In an electric circuit comprising a main portion and a branch derivedtherefrom. the combination of means in the main portion for opening thecircuit under conditions of excessive current flow and circuit breakermeans in the branch responsive to like conditions therein which opensafter the means first mentioned has eflectually broken the circuit.

5. In an electric circuit compris In portion and a branch derivedtherefrom, the combination of a circuit breaker in the main portionrcsprnisire to conditions of excessive current new and circuit breaker.nieans in the branch responsive only to current flow heavy enough tobring about the opening of said first mentioned circuit hreal-zer thatopens after the first mentioned circuit breaker vhas effectually brokenthe circuit and remains open when the first mentioned circuit breaker isclosed again, so that the branch remains efl'ectually cut ofi 6. in anelectric circuit comprising a main portion and a branch derivedtherefrom, the combination of a circuit breaker in *he main portionresponsive to conditions of excessive current ilow therein, circuitinterrupting means in the brancln and means responsive to conditions ofexcessive current flow in the branch which causes said circuitinterruptnormally not in immediately operative con- 8. In an electriccircuit, the combination of a circuit breaker responsive to conditionsof excessive current flow, additional circuit interrupting 1n ans thatautomatically tends to open a detent for normally preventing suchopening, a latch adapted to serve as an ope alive connection forreleasing said detent, a catch adapted to engage and operate on saidlatch which tends to occupy an inoperative position out of engagementtherevith, and elcctroniolivc means o icrating under conditions ofexcessive current flow in the circuit for moving said catch past saidiatch into operative position with reference thereto so that said detentmay he tripped when the circuit is broken by the opening of said circuitbreaker.

in witness whereof, I have hereunto set my hand this Q-Llth day ofDecember, 1913. ,irlLBERT WRIGHT.

Viitnesscs:

Bnxaann: B. Hone,

HELEN Onronn.

